Apply for SURF and SURG grants with the help of a faculty mentor.
Take 36-315: Statistical Graphics and Visualization.
This was one of the most useful classes I took, both for interships and graduate school!
Become familiar with dplyr, ggplot2, and R Shiny even if you do not take 36-315.
Write your name in color on all your homework assignments so that you can find it quickly when professors hand homework back in a big pile at the end of class.
Make friends with a student a year or two above you in your program.